Flying form trusses are used to form concrete floors in multi-story structures. Some flying form truss systems transmit the poured concrete load directly to the floor slabs below and in fast construction cycles, the concrete floor below may not be fully cured. For this reason, reshoring of the lower concrete floor may be necessary to transmit the loads to a slab which is fully cured. Reshoring takes additional time and also limits the access to some lower levels which are effectively cured.
To overcome the above problems, it is known to use column mounted flying form truss systems designed to transfer the concrete load to the columns as opposed to the lower floors. Column mounted truss systems allow full access to the lower floors and the follow-up trades can be working on any floors which have been previously poured. With this arrangement, the construction cycle can be reduced.
Column mounted flying truss systems are most commonly used with flat slab construction but can accommodate shallow internal beams and spandrel beams. Any projection from the slab soffit increases the stripping distance the support jacks must lower the truss to allow removal.
Flying form systems typically use two large I-beams which run parallel to the building support columns with the I-beams being supported by shoring jacks secured to the columns. The shoring jacks are adjustable in height and typically have a roller associated therewith to allow lowering of the I-beams and sliding of the truss out of the formed bay. These I-beams have a series of transverse beams secured to and extending perpendicular to the I-beams. A series of runner beams which typically support a plywood deck are secured and extend perpendicular to the transverse beams.
The construction design of the building in combination with the expertise of the contractor typically determine whether a column hung truss system or a shoring frame truss system will be used. Column hung truss systems are often used for condominium and hotel construction, particularly when a short construction schedule is needed.
The transverse beams are of a length which is primarily determined by the width of the bays used in the building. The bay width is the distance between the columns. Surprisingly the bay width of different buildings varies substantially and thus different lengths of transverse beams are required. It is known to use composite transverse beams formed using U-shaped channel sections placed in back to back relationship and secured in an overlapping adjustable manner. Typically mechanical fasteners are used to secure the channels to form the appropriate length of transverse beams. It is desirable to produce relatively stiff transverse beams such that the spacing between the beams can be large, thereby reducing the number of transverse beams required and reduce the weight of the system. It is desirable that the overall weight of the flying truss be reduced to ease the movement thereof and to accommodate the crane capacity used for the building construction.
The present invention provides improvements to the transverse beams and improvements to truss systems used in concrete forming.